Acute Mountain Sickness or altitude sickness is pretty awful and can even be fatal. It affects people who are not acclimatised to being at high altitude. The higher you go the less oxygen is available to you per breath, until you acclimatise.
Altitude sickness sets in when your body cannot adapt quickly enough to reduced oxygen intake at higher altitudes. It is difficult to tell who will be affected and when - there are no determining factors, although the most serious symptoms usually appear after 3 700 metres (12 000 feet).
Many climbers will experience hangover or flu-like symptoms within 12 to 24 hours of acclimatisation at altitude, which generally subside after 48 hours. The symptoms are worse during increased exertion and at night.
Mild symptoms in order of appearance are headache, nausea / dizziness, no appetite, fatigue, shortness in breath, rapid pulse, insomnia, apathy / depression. These effects will wear off as the body adjusts and climbers should be able to continue at a slow pace.
The next stage is increased severity of the mild symptoms plus vomiting and some co-ordination loss, at this point immediate intervention is required to move the person to a lower altitude until acclimatised.
An increase of the 2nd stage symptoms plus swelling of hands and feet will move the condition to a severe status. If the person cannot walk unaided then a stretcher evacuation is essential. Any build up of fluid on the lungs or on the brain that does not receive immediate treatment could be fatal.
Seek good advice from your physician with regard to taking altitude sickness medication. Taking the time to acclimatise is a very important step and should never be overlooked or hurried. Your body needs time to adjust so it can function optimally. The more time you spend on this step the higher your chances are of reaching the summit.
Walk slowly. With every step your body is working hard to adjust to the environment. Allocating rest days will increase your ability to ascend to the summit considerably and you will enjoy the experience much more.
Drink a minimum of 4 litres of liquids (water is the best) each day. You will have to carry screw top bottles initially (fresh water can be bought in Moshi) until you are higher up the mountain where water can be sourced from flowing streams. Of course, running mountain water may not agree with you so prevent any tummy upsets by taking along a method of purifying the water - there are a variety of options but tablets that you can drop in to your drinking water may be the easiest to carry.
You should carry a range of high calorie foods to eat along the way, even if you don't feel hungry. This will keep up your strength and give your body fuel to deal with the physical demands of the hike.
It is recommended that you take a walk to a higher level on the mountain before coming back down to sleep at night. Most reputable operators incorporate this technique into their expeditions.
Even if you feel strong and confident, a fast ascent to higher levels is sure to bring on mountain sickness. Don't go up until symptoms have subsided. Keep going down if symptoms increase. Moving to a lower altitude and staying there until your body has adjusted and symptoms have ebbed away is a common solution to persistent altitude sickness.
Avoid the use of alcohol, tobacco and drugs such as tranquilisers, opiates, barbiturates and sleeping tablets, as these will have an adverse effect on your body and increase the symptoms of altitude sickness.